[lwip-devel] [bug #20021] conn->sem is only signaled one-way

[Jonathan Larmour]

Follow-up Comment #13, bug #20021 (project lwip):

The existing behaviour of netconn_write is to block and wait if out of mem or
send window, so to preserve that, the calling thread would block in
tcpip_apimsg waiting for the sys_arch_mbox_fetch (or whatever replaces it,
from Frederic's work) to return. The tcpip thread would only wake it up when
it really does complete. So I think you can guarantee someone is waiting
because that's where they will be blocked.

That seems the best approach that would avoid race conditions, to me, but
there are probably others.

NB I'm going on vacation this weekend, so won't be able to contribute more to
this discussion after tonight.... I just say that in case you direct something
to me and I don't answer :).



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